Support for filament assemblies



\ 2 1946; R. A. NELSON ETAL 2,410,993

SUPPORT FOR FILAMENT ASSEMBLIES I Filed Sept. 4, 1944 2' Sheets-Sheet 1 Z6 25 i 2 H I III 72 I I II I l 10 i H ijl axiom Nov. 12,1946. R. A..NELSON ERAL 2,410,993

SUPPORT F on FILAMENT ASSEMBLIES Filed Sept. 4, 1944 2 SheetsSheet 2 (b) I. Ffg.., 4.

Reuben fl. Nelson William -O. Smizh Patented Nov. 12, i946 "ii-trap SUPPORT FOR FILAMENT ASSEPMLIES Reuben A. Nelson, Sllgo Park Hills, and William 0. Smith, Silver Spring, Md.

Application September 4, 1944, Serial No. 552,664

(Cl. 1'l639) (Granted under the m of March a, 1883, as amended April 30,1928; 370 o. e. 357) 2 Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, it patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a support for filament assemblies and more particularly to a support for filaments in incandescent lamps, electron tubes, and other devices using filaments.

In a lamp of this sort where maximum radiationis desired at a uniform temperature, and it is necessary to use a multiplicity of strands of straight tungsten filament, all of these lying in a single plane and close together, it becomes quite difficult to form and support the tungsten filament so that each of the segments is straight,

of the same length and does not touch other segments, and moreover remains in this condition when heated to extremely high temperatures. Due to the excessive expansion of the refractory filament when heated, means must be provided to compensate for this expansion which will not at the same time introduc harmful and deleterious strains and distortion tending to shorten the life of the filament. It is desirable also that the supporting member be such as to provide a means for straightening and aligning the several or segments while they are heated to high temperature.

According to one embodiment of this invention, these objects are attained by a filament-supporting assembly comprising a standard (or pedestal or arbor or rod) mounted upon or extending upward from the stem, a crosspiece or bracket attached to the top of the standard and perpendicular thereto, a main crossarm suspended from the bracket by a coiled spring and rotatable in a vertical plane (11. e. about a horizontal axis through its point of support), two short crossarms of electrically insulating refractory material such as quartz, suspended from the ends of the main crossarm after the manner of singletrees supported by, or attached to, the ends of a'doubletree; and wire hook members of a highly refractory metal for suspending the multiple strands of filament from the ends of the insulating crosspieces.

Other objects, advantages, and features of this invention will appear more particularly from the following description.

of distributing tension equally among all strands or loops of the filament. I

A further object is to support the filament by an insulated member capable of compensating for the expansion of the filament upon heating it tohigh temperature, and keeping the separate strands uniformly taut but not under excessive unequal tension.

Still another object is to provide a means for straightening the filament after it has been mounted, sealed into an envelope (or bulb), and evacuated or surrounded by inert gas, by applying a small, uniform tension equally to all strands Referring to the drawings which form a part of this specification:

Figure l is a perspective elevation of a lamp illustrating a filament assembly support constructed according to this invention,

Figure 2 shows another form of supporting structure embodying this invention such as could be used either in a lamp or in an electron-emitting device,

Figure 3 is a detail view of a simplified modification of a portion of the supporting structure, and

Figure 4 is a schematic elevation of modification of the suspension assembly when more than four points of support are required, (a) showing 6 points of support, and (b) showing 5 points.

justment of the collar upward or downward on the pedestal. The collar is drilled to hold a supporting rod or crosspiece 20 perpendicular to the pedestal and secured by a setscrew 2!. A spotweld construction may also be used. Suspended from this support is the resilient self-equalizing filament-supporting member by means or which all parts of the filament are maintained under uniformly equalized tension. This comprises a helical spring 22 of a refractory metal, such as molybdenum, capable of retaining its resiliency at high temperatures, supported from the crosspiece 20, and supporting from its lower end the rocker arm 23, the point of support in this embodiment being at the center of the rocker arm. Supported from each end of the rocker arm 23, by means of wire hook members 24, universally movable at the point of support, is a crossarm 25 of an insulating material such as quartz, likewise universally movable about its central point of support. Supported from each end of the insulating crossarm are the wire hook members 26. The attachment of the wire hook members 24 and 28- to the insulating crossarm 25 may be accomplished by forming grooves at its center and end in a suitable manner such as by grinding, the wire hook members 26 being then looped loosely about grooves and fastened by twisting the loose ends about the standing part.

A filament 2'! of a refractory metal, such as tungsten, is suspended between the hooks 26, the leading-in conductors l4 and I5, and the fixed supporting hooks 28.

In the modification of the filament-supporting structure embodying this invention shown in Figure 2, a collar 30 surrounding the re-entrant stem I 2 of the tube I I, and clamped to said stem by some means such as bolts, supports the vertical standards 3 I, connected at their upper ends by the crosspiece 32. Supported from said crosspiece 32 is the self-compensating, filament-suspension device comprisirig spring 22, rocker arm 23, wire hook or link members 24, insulating crossarm 25 and wire filament-supporting hooks 26. The transverse insulating guide block 33 is supported on the vertical standards 3|, and is provided with vertical slots 34 through which pass the wire hook-members 26. Guide block 33 is positioned about midway between the point of attachment of wire hook members 26 to insulating crossarms 25 and the filament-supporting hook at their extremities. The long axes of slots 34 are parallel to the long axis of the guide block and to the plane of the filaments, thus restricting horizontal lateral motion but permitting sufiicient horizontal longitudinal displacement in order to allow the necessary adjusting action to occur. The filament is suspended be-' tween the hooks 2B and the leading-in conductors l4 and I and a lower suspension system which may be fixed hooks as in Figure 1 or alternately' as shown in Figure 2 may be another system similar to the upper suspension system comprising a spring 35 supporting rocker arm 36 at a point dividing it into segments whose lengths are in the ratio 1:2. suspended from the end of, the short segment by means of a wire hook member is an insulating crossarm 31, centrally supported and carrying at its ends wire hook members 38 which support segments of the filament. Suspended from the long end of rocker arm 36 through an insulating glass or ceramic head is a third wire hook supporting the third loop segments of filament.

Various modifications may be made in the application of this invention to incandescent lamps,

electron discharge tubes, or other similar devices without departing from the scope and spirit of this invention as defined in the appended claims.

Having thus described our invention, what is claimed is:

l. A support for filament assemblies having a plurality of segments of the type which are mounted in sealed envelopes, which comprises a standard mounted in said envelope, a crossarm yieldably supported on said standard and rotatable about an axisthrough its point of support perpendicular to the plane of the filament segments, insulating members supported from each end of and lying in the same plane as said crossarm and universally movable with respect to said crossarm, said members being rotatable in said plane in the manner of a singletree, hook members arranged on said insulating members for supporting one end of said segments, said crossarm, insulating members and hook members being assembled all in one plane after the manner of singletrees attached to a multiple tree, and hook members mounted in said envelope to support the other end of said segments.

2. A support for filament assemblies having a plurality of segments of the type which are mounted in sealed envelopes, which comprises a standard mounted in said' envelope, a crossarm yieldably supported on said standard, insulating members universally mounted at each end of said crossarm, hook members arranged on said insulating members for supporting one end of said segments, said crossarm, insulating members and hook members being assembled all in one plane after the manner of a multiple singletree, and hook members mounted in said envelope to support the other end of said segments. 

